A first technique for repairing a hole in a building panel, such as a wallboard or drywall, involves filling the hole with scrunched up paper or a piece of wood and applying layers of plaster until the repair is considered to be satisfactory.
A problem with this technique is the unpredictability of the integrity of the repair. The technique involves an irregular distribution of plaster throughout the restoration area. A differential cure rate across the repair, due to different depths of plaster within the filled hole or fluctuations in temperature and humidity, is a contributing factor towards cracking.
In addition, during curing, plaster contracts and the application of an insufficient quantity of plaster in an area can also lead to cracking. The technique also involves the use of a porous fill material, and absorption of water from the plaster by the fill material can lead to dehydration cracking. The potential quality of the repair is deteriorated during curing by interacting factors contributing towards cracking, often leading to a repair of unsatisfactory quality requiring patching.
A second technique for repairing a hole in a hollow building panel described in U.S. Pat. No. 4,193,243 involves the insertion of a perforated sheet through the hole and is then mounted to the building panel using a tool and rod arrangement inserted through the perforated sheet. A problem with this technique is that the tool and rod arrangement may become lost or broken in a building environment and is inconvenient to use. Following mounting of the perforated sheet, the outer portion of the rod must be broken off and the tool removed. This is inconvenient in practice and may weaken the quality of the mounting of the perforated sheet to the building panel. In addition, the apparatus used in the repair presents an obstruction to subsequent mounting of an object to the repaired area of the building panel.
A third technique for repairing a hole in a building panel involves applying a mesh patch to the front surface of the building panel to cover over the hole and to which plaster or other compound is then applied. When dry, the plaster or other compound is sanded down. A disadvantage with this technique is that in most cases, a bump is left on the building panel surface. Such a bump may present an obstacle if tiling over the repair. Furthermore, a relatively small amount of plaster or other compound is used to complete the repair. This characteristic of the repair renders the repair susceptible to damage, for example, in the event an object strikes the building panel in the area of the repair, and also reduces the ability of the building panel to support fixings in the area of the repair.